My washing machine drain hose has started backing up the drain pipe when the tub is emptying, overflowing into my laundry room. This is the same washing machine I've had for at least 5 yrs. i am concerned that the original plumbing in the drain line may be setup wrong, even tho it's been working fine for years. Right now, the drain hose from the washer loops down and then back up before going into the main drain pipe at the box behind the washer. (Not sure this is an effective p-trap). The main pipe goes straight down into the foundation. There's a t joint off one side of this main pipe that goes about 3 inches horizontally, then turns 90 degrees going up to the roof. (I'm guessing this is the vent, It is is not clogged. Is it vented wrong??) I have tried drano, and a water hose in the vent and main drain. The water always starts flowing, then I can gradually hear it backing up the pipe till it reaches the top and overflows. After I stop the washer(or hose) and let it flow on down, it makes a gurgling sound for a couple minutes. I don't know a lot about plumbing, but would like to learn how to resolve this myself. Thank you for any help!!

from your description either it has NO "P" trap, or the "vent" is improper and ineffective. Your drain probably just needs snaking, and "Drano" is completely useless, as is vinegar and baking soda, or any other "chemical".

Snaking is the next plan. Do you think I should address the lack of p-trap, or vent problems, too, even if snaking fixes the slow drain??

definitely. I think it may be a violation of code.

Over the years, your washing machine drain has been attracting lint and debris. Add soap grease and you have the perfect recipe for a pending clog. The inside of your pipe must be scraped, cleared and cleaned.
The obvious remedy is a professional cleaner..... a license plumber. Once the drain is cleared n clean, have the plumber look for code issues.
Best Wishes

quote; . Do you think I should address the lack of p-trap, or vent problems
1. You do not really know if you have a "lack of a P trap", and
2. We are using your description to determine that you have a "vent problem"
3. Until you know whether either of these items are actual, you cannot do anything.

Thanks for the help! Once I get the line cleared, I am going to get someone to check the code issues. Thanks again!!



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I would just have a camera guy peep in your pipe to see what`s going on.